Most vibratory devices, such as material tamping devices, pile drivers, vibrating tables, wick drain devices and fruit-tree shakers and the like, create desirable vibration by rotating eccentrics. In these devices, due to the wear and tear and heat resulting from vibrating machinery, it is desirable to have continuous lubrication of various internal components such as the meshing gears, bearings, and the eccentrics. Such lubrication serves to cool the intermeshing and interacting internal components that generate heat by their movement and interactions between parts. In much the same way as an automobile engine will cease up without oil to lubricate and cool the engine, pile drivers, wick drains and the like would quickly overheat and possibly cease up without lubrication to cool and lubricate its internal parts. Heretofore, the continuous lubrication used to cool and lubricate a pile driver or vibratory wick drain device has been of two types, one by fluttering and the other by nebulization.
Generally, “nebulized” lubrication involves throwing lubricant sprays onto the bearings and other components susceptible to heat and wear. The excess lubricant (e.g., oil) is collected in a recovery basin and then returned from the basin to the spraying nozzles by a motorized pump. This type of lubrication is performed in a free atmosphere. In some embodiments of nebulized lubrication, the bearings are force-lubricated by directing the lubricant directly into sealed bearings and returning excess lubricant to a recovery basin that is separated from the interior of the gear box by a wall that keeps the lubricant out of the interior of the gear box.
A drawback to nebulized lubrication is that it typically requires a vibration-tolerant motor to drive the pump, which adds significant weight and cost to the system and requires a power source for the motor, reducing the overall efficiency of the vibratory device. Additionally, because the meshing gears, bearings, and eccentrics are enclosed within the gear box, they are hidden from the operator's view. Consequently, if the motorized pump or any part of the pumping system fails, the operator frequently will not know of the failure until after serious damage to the vibratory device has occurred. Vibratory devices have been known to cease up due to lack of lubrication when the lubricant pumping system unknowingly fails.
Lubrication “by fluttering” has been performed both in a free atmosphere and under vacuum. Generally, this type of lubrication involves driving the eccentrics into rotation within a lubricant container or reservoir. The lubricant is thrown by the centrifugal force of the eccentrics. Particularly with eccentrics that have a semi-circular profile, rotation of the eccentric around its axis causes the eccentric to impact against the lubricant within the container or reservoir. This causes lubricant splash within the gear box (or housing) and forces the lubricant against the interior walls of the gear box. At startup of the vibratory device, this impact is generally rather strong, although it depends on the diameter of the eccentric, its thickness, and the level of and viscosity of the lubricant. Such impact, retards the rotating momentum of the eccentric and absorbs energy making the vibratory device less efficient than it could be if this impact were significantly reduced or eliminated. So long as the lubricant is regularly changed and appropriate levels of lubricant are maintained, the lubricant is always present within the gear box. However, during operation of the vibratory device following startup, the lubricant is so violently agitated, both by the vibration and from eccentric impact, that much, if not all, of the lubricant becomes a fine mist of lubricant globules suspended within the interior volume of the gear box.
Because the bearings are most susceptible to overheating and wear, lubrication of the bearings is usually the highest priority with vibratory devices. Although the fine mist of lubricant lubricates the internal components of the vibratory device, including the bearings, the gear box is an enclosure that holds the heat generated within the gear box. With most uses of vibratory devices the rapid heating of the device is not a serious problem because most vibratory devices are designed for intermittent duty (e.g., it takes a short period of time to drive a pile and then the vibratory device is allowed to rest from vibrating and cool down until another pile is attached and ready to be driven). However, the need for continuous duty vibratory devices is increasing. For example, vibratory wick drain devices operate almost continuously because there is such a short time between driving each wick drain. Also, as the advantages and various uses of vibratory devices become better known, the need for continuous duty pile drivers is increasing.